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X-2

The X-2 was a swept-wing aircraft designed to fly three times faster than the speed of sound [Mach 3] and at altitudes above 100,000 ft. It was flown to investigate the problems of aerodynamic heating and stability and control effectiveness at high speeds and altitudes.

The X-2 was a single-place airplane with wings swept back to 40 degrees. It was 37 ft, 10 in. long, 11 ft high and had a wingspan of 32.3 ft. It was constructed constructed of K-monel (a copper and nickel alloy) for the fuselage and stainless steel for the swept wings and control surfaces. The aircraft had ejectable nose capsules instead of ejection seats because the development of ejection seats had not reached maturity at the time the X-2 was conceived. The X-2 ejection canopy was successfully tested using a German V-2 rocket. The X-2 used a steel belly-skid main landing gear and a short, unsteerable nose wheel to conserve fuselage space for more internal fuel. The X-2 was powered by an XLR25-CW-3 two-chambered throttleable rocket engine. The Curtiss-Wright manufactured engine had a thrust of 15,000 lb. Two X-2s were made for the Air Force by Bell Aircraft Company of Buffalo, New York. The airplane was air launched from a modified Boeing B-50 Superfortress Bomber.

Providing adequate stability and control for aircraft flying at high supersonic speeds was only one of the major difficulties facing flight researchers as they approached Mach 3. For, at speeds in that region, they knew they would also begin to encounter a "thermal barrier"--severe heating effects caused by aerodynamic friction. The sweptwing Bell X-2 was designed to probe this region and to be the first aircraft to take man well above the measurable atmosphere to the very edge of space.

Following launch from a modified B-50 bomber, Bell test pilot Jean "Skip" Ziegler completed the first unpowered glide flight of an X-2 at Edwards on June 27, 1952. This aircraft was subsequently lost lost in an in-flight explosion while at the Bell Aircraft Company during captive flight trials and was jettisoned into Lake Ontario. The Air Force had previously flown the aircraft on three glide flights at Edwards Air Force Base, California, in 1952.

Lt. Col. Frank K. "Pete" Everest completed the first powered flight in the second airplane on November 18, 1955 and, by the time of his ninth and final flight in late July the following year, he had established a new speed record of Mach 2.87 (1,900 mph). The X-2 was living up to its promise, but not without difficulties. At high speeds, Everest reported that its flight controls were only marginally effective. Moreover, simulation and wind tunnel studies, combined with data from his flights, suggested that the airplane would encounter very severe stability problems as it approached Mach 3.

A pair of young test pilots, Captains Iven C. Kincheloe and Milburn G. "Mel" Apt, were assigned the job of further expanding the envelope and, on September 7, 1956, Kincheloe became the first pilot ever to climb above 100,000 feet as he flew the X-2 to a peak altitude of 126,200 feet.

Just 20 days later, on the morning of 27 September 1956, Mel Apt was launched from the B-50 for his first flight in a rocket airplane. He had been instructed to follow the "optimum maximum energy flight path" and to avoid any rapid control movements beyond Mach 2.7. Flying an extraordinarily precise profile, he became the first man to exceed Mach 3 that day, as he accelerated to a speed of Mach 3.2 (2,094 mph) at 65,500 feet. The flight had been flawless to this point but, for some reason, shortly after attaining top speed, Apt attempted a banking turn while the airplane was still well above Mach 3 (lagging instrumentation may have indicated that he was flying at a slower speed than he was or perhaps he feared he was straying to far from the safety of his landing site on Rogers Dry Lake). The X-2 tumbled violently out of control and he found himself struggling with the same problem of "inertia coupling" which had overtaken Chuck Yeager in the X-1A nearly three years before. Unlike Yeager, however, Apt was unable to recover and both he and the aircraft were lost.

While the X-2 had delivered valuable research data on high-speed aerodynamic heat build-up and extreme high-altitude flight conditions, this tragic event terminated the program before the National Advisory Committee for Aeronautics could commence detailed flight research with the airplane and the search for answers to many of the riddles of high-Mach flight had to be postponed until the arrival, three years later, of the most ambitious of all the rocket planes -- the X-15.



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